Electrosurgical tools have been available for many years which employ electrical energy to treat targeted patient tissue in various ways. For example, electrocauterization is utilized to seal off and close blood vessels during surgery to prevent blood loss. In addition, ablation is utilized to vaporize or remove tissue using electrical energy. Electrosurgical probes are typically designed to perform both of these functions, depending upon the type of power supplied thereto. Further, monopolar and bipolar electrosurgical tools have long been available, wherein monopolar tools direct electric current from an active electrode defined on the tool through the patient's body and to a return electrode, which return electrode is typically defined by a grounding pad attached to the patient. Bipolar tools, on the other hand, incorporate both an active and a return electrode directly into the tool.
Surgical procedures utilizing bipolar tools are often performed using a conductive irrigant, such as saline, for irrigation and for distending a joint, for example in orthopedic arthroscopic procedures. The conductivity of the saline solution provides a conduction pathway between the active and return electrodes of the tool. The delivery of a high-frequency current between the active and return electrodes effectively modifies tissue, and it is common for bubbles to form on the surface of the tool or probe tip which can interfere with the surgeon's view of the surgical site. This is particularly a problem when the electrosurgical tool is employed in an endoscopic surgical procedure, wherein the tool is inserted into the surgical site through a small opening or portal formed in the patient's body. The surgeon views the surgical site through an endoscope which is inserted into the surgical site through another portal. Thus, these bubbles are generated in the relatively small confines of the surgical site and cause significant problems for the surgeon in viewing the surgical site. Further, the bubbles are electrically and thermally insulating, and can inhibit the flow of new saline solution for rewetting the electrode. Consequently, the bubbles can cause undesirable reduction of current flow through the targeted tissue.
In order to address the undesirable bubble generation described above, and also so as to allow the ability to remove treated tissue and other debris from the surgical site, some electrosurgical tools incorporate a suction feature. One type of electrosurgical tool manufactured by the Assignee hereof includes an outer conductive shaft which is covered with an insulating material. The distal end of the shaft is exposed from the insulating material, and serves as a return electrode. The active electrode is supported at the shaft tip by an insulator cap, typically constructed of ceramic. The insulator cap is mounted within the open distal end of the shaft, and defines therein two bores. The distal end of the active electrode extends through one of these bores, and a plastic suction tube extends inside and along the outer shaft and into the other bore. This arrangement thus permits a vacuum to be drawn through the tool from the distal end thereof.
Minimally invasive surgical techniques require surgical tools to be as small as possible in order to minimize trauma to the patient. As such, there is an ongoing effort to reduce the size of surgical instruments whenever possible. While the above tool works reasonably well for its intended purpose, the requirement for the outer shaft to house both a suction tube and wiring for delivering current to the active electrode can present difficulties in assembly of the tool. Further, this arrangement results in limited available space within the outer shaft, which places a limit on the diameter of a suction tube. In an effort to effectively reduce the overall size of the electrosurgical tool and simplify assembly thereof, the Assignee hereof integrated the functions of suction and energy delivery to the active electrode into one component of the electrosurgical tool. Such a tool is disclosed in U.S. Patent Publication No. US2006/0235377. This tool incorporates an electrically conductive inner shaft which defines both a suction path though the tool and an energy-delivery path to the electrode located at the distal end of the tool, which eliminates the need for wiring extending through the tool and reduces the overall size of the tool.
A further problem with electrosurgical tools having suction capability is clogging. In this regard, in electrosurgical tools having an electrode with a geometry of a plate, box, full or partial sphere, doughnut, cone or pyramid, for example, and having the electrode attached or supported by an insulating component, such tools typically have a suction opening that is fully or wholly defined by the electrode itself. When the treating portion or face of the electrode is in full or substantially complete contact with tissue, suction through the opening or openings in the electrode face can be temporarily stopped. This flow stoppage can cause charred or partially ablated tissue to become lodged or stuck on the face of the electrode and across the suction openings defined therein. Then, when the probe is removed from the tissue, the charred tissue often continues to cover the suction openings, which clogs the tool.
In an effort to minimize clogging of an electrosurgical tool as discussed above, the instant invention provides a suction opening or pathway which is defined by both the electrode and the insulator element or cap which supports the electrode on the tool. Providing a suction opening defined by the two different materials of the electrode and the insulator reduces clogging in that while charred tissue may adhere to the electrode, any charred tissue located near the insulator either does not adhere to the insulator or adheres less strongly to the insulator, so that when the suction flow resumes once the electrode is removed from contact with the tissue, any charred tissue located on the insulator is easily removed by suction. The above arrangement thus minimizes the adherence of charred tissue to the working tip of the tool, and allows easier dislodgement of any charred tissue to the working tip to maintain greater and more continuous suction flow through the tool. At least one additional suction opening can also be provided at the working tip of the tool, which opening is defined wholly by the electrode.
The above arrangement which includes at least one suction opening defined by the electrode and the non-conductive insulating element which supports the electrode can also increase the size of the suction opening at the working tip of the tool, in that the suction opening is not fully surrounded and defined by the material of the electrode itself. Providing a larger suction window or opening at the tool tip can make it more difficult to cut off the flow of suction through the tool when the electrode face is fully or largely in contact with tissue, and the more suction that is being drawn through the tool, the less chance of a clog. In this regard, when the suction flow is stopped within the tool, even if the stoppage is temporary, small pieces of tissue can deposit on nearby surfaces and cause particulate clogging within the interior of the tool.
Further, in electrosurgical tools used for mass ablation of tissue, the tool shaft and the treating surface of the electrode or electrode face are often oriented generally parallel to one another, i.e. the tool or probe is fairly sharply angled at its distal end. This configuration allows improved access to targeted areas within the surgical site, such as in a joint. However, an angled probe configuration means that the suction pathway at the distal end of the tool has two portions which are oriented transversely relative to one another, which can make clogging more frequent due to the somewhat convoluted path through which the pieces of tissue must travel after being drawn into the tool. The arrangement according to the invention is thus particularly useful in these types of tools, as same can significantly reduce the possibility of clogging of the tool.
The electrode according to the invention is also advantageous in that same incorporates reinforced areas of metal adjacent open areas of the electrode which define suction openings, which provides the electrode with improved strength and durability. Specifically, thinner areas of the electrode are provided generally centrally or inwardly on the tissue-treating surface of the electrode adjacent to suction openings formed in the treating surface of the electrode. Reinforced or thickened areas are provided on the treating surface of the electrode outwardly of these thinner areas. The thinner areas can experience wear or degradation during usage of the probe due to the passage of current therethrough. However, the reinforced areas effectively maintain the electrode intact and can provide a longer-life tool.
Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. The words “forwardly” and “distally” will refer to the direction toward the end of the arrangement which is closest to the patient, and the words “rearwardly” and “proximally” will refer to the direction away from the end of the arrangement which is furthest from the patient. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.